Biological Sciences, School ofThis community contains research by faculty members and students in the School of Biological Sciences at Washington State University.http://hdl.handle.net/2376/6992019-01-22T01:20:33Z2019-01-22T01:20:33ZThe functional morphology of hooding in cobrashttp://hdl.handle.net/2376/26612017-09-26T23:11:21Z0005-01-01T00:00:00ZThe functional morphology of hooding in cobras
Many snakes, particularly cobras, form as part of a defensive display, a hood, an active lateral expansion of their neck skin and underlying musculature and ribs. We identified muscle groups possibly involved in hooding based on their attachments on the
specialized ribs of the neck. We then used a combination of morphology, kinematic analysis, morphometrics, electromyography
and muscle stimulation to test hypotheses about the functional basis of hooding. We confirmed that hood protraction and
erection is an active process that begins cranially and extends caudally, often in stages, through the combined action of several sets of muscles. One set of axial muscles (levator costae and supracostalis lateralis superior) coursing along a line of action to rib displacement are the prime erectors acting to lift the hood. However, a second set of muscles connecting ribs to skin primarily keep the skin taut, rather than to displace the ribs relative to the vertebrae. A third set of muscles coursing between ribs function primarily to transmit forces between adjacent ribs rather than to move ribs. The maintenance of the erect hood requires continued muscle activity. Hood relaxation is due to both active muscle contraction of a fourth set of axial muscles and to passive recoil events in the costovertebral ligaments. The shape of the fully erect hood is reflective of the morphometrics of the underlying ribs,
while the duration and kinematics of hood erection and relaxation are related to the behavioral context of the display.
0005-01-01T00:00:00ZPredation on the Invasive Copepod, Pseudodiaptomus forbesi, and Native Zooplankton in the Lower Columbia River: An Experimental Approach to Quantify Differences in Prey-Specific Feeding Rateshttp://hdl.handle.net/2376/58052017-09-26T19:23:09Z2015-01-01T00:00:00ZPredation on the Invasive Copepod, Pseudodiaptomus forbesi, and Native Zooplankton in the Lower Columbia River: An Experimental Approach to Quantify Differences in Prey-Specific Feeding Rates
Invasive planktonic crustaceans have become a prominent feature of aquatic communities worldwide, yet their effects on food webs are not well known. The Asian calanoid copepod, Pseudodiaptomus forbesi, introduced to the Columbia River Estuary approximately 15 years ago, now dominates the late-summer zooplankton community, but its use by native aquatic predators is unknown. We investigated whether three species of planktivorous fishes (chinook salmon, three-spined stickleback, and northern pikeminnow) and one species of mysid exhibited higher feeding rates on native copepods and cladocerans relative to P. forbesi by conducting `single-prey’ feeding experiments and, additionally, examined selectivity for prey types with `two-prey’ feeding experiments. In single-prey experiments individual predator species showed no difference in feeding rates on native cyclopoid copepods (Cyclopidae spp.) relative to invasive P. forbesi, though wild-collected predators exhibited higher feeding rates on cyclopoids when considered in aggregate. In two-prey experiments, chinook salmon and northern pikeminnow both strongly selected native cladocerans (Daphnia retrocurva) over P. forbesi, and moreover, northern pikeminnow selected native Cyclopidae spp. over P. forbesi. On the other hand, in two-prey experiments, chinook salmon, three-spined stickleback and mysids were non- selective with respect to feeding on native cyclopoid copepods versus P. forbesi. Our results indicate that all four native predators in the Columbia River Estuary can consume the invasive copepod, P. forbesi, but that some predators select for native zooplankton over P. forbesi, most likely due to one (or both) of two possible underlying casual mechanisms: 1) differential taxon-specific prey motility and escape responses (calanoids > cyclopoids > daphnids) or 2) the invasive status of the zooplankton prey resulting in naivety, and thus lower feeding rates, of native predators feeding on invasive prey.
2015-01-01T00:00:00ZA phylogenetic analysis of the genus Mertensia (Boraginaceae): taxonomy, divergence times, and biogeographyhttp://hdl.handle.net/2376/47462017-10-05T20:18:45Z2013-01-01T00:00:00ZA phylogenetic analysis of the genus Mertensia (Boraginaceae): taxonomy, divergence times, and biogeography
This study explores the taxonomy, systematics, and biogeography of
Thesis (Ph.D.), Botany, Washington State University
2013-01-01T00:00:00ZExploring the life histories of cephalopods using stable isotope analysis of an archival tissuehttp://hdl.handle.net/2376/47742017-10-05T20:25:24Z2013-01-01T00:00:00ZExploring the life histories of cephalopods using stable isotope analysis of an archival tissue
Relatively little is known about the life histories of cephalopods compared to many other groups of major marine predators such as fish, marine mammals, and sea birds. Increased importance of cephalopods to global fisheries in the past forty years and a recognition of the important ecological roles of cephalopods has driven increased research interest into the lives of these enigmatic animals. Still, there is a paucity of information about the life histories of all cephalopods except a few well-studied species.Stable isotope analysis has become a powerful tool to infer nutritional sources and movement patterns in aquatic organisms. The use of this tool can be extended temporally when used in tissues that have no elemental turnover after formation, or archival tissues, which provide a frozen record of stable isotope composition at formation. In this dissertation I explore the utility of using stable isotope analysis of an archival tissue, eye lens, in cephalopods to help provide sorely needed information about the life histories of this ubiquitous class of marine mollusks. Here the use of stable isotope analysis of eye lenses is used to investigate possible natal origins of
Thesis (Ph.D.), Zoology, Washington State University
2013-01-01T00:00:00Z